1. Field of the Invention
This invention relates to gradient refractive index devices with particular reference to improvements in method of making columnar gradient refractive index lens elements for ommateal lenses or face plates.
2. Discussion of the Prior Art
A variation of the radially graded multi-ocular lens or face plate component is the "cylindrical" gradient power columnar element in which the refractive index gradient extends transaxially, i.e. from the element axis toward its opposite side, and is substantially uniform from front to back at each increment of gradation. This basic configuration has been described in U.S. Pat. No. 3,667,832.
The manufacture of such a lens or face plate component has, however, involved tedious, costly and usually less than accurately continuously reproducible processing techniques which, for example, involve the exposure of a side of a glass plate to an oxide modifying salt for ion exchange and cutting of the thus treated plate into a multiplicity of lens components of proper size and shape, each requiring grinding and optical polishing of the cut surfaces prior to final assembly.
Typical prior art cycles for ion exchange processing require as many as hundreds of hours using generally messy and difficult to handle ion exchange agents, added to which are the aforesaid costly and time consuming article cutting and element-by-element surface finishing operations.
In the interest of simplifying gradient refractive index ommateal lens manufacturing operations and reducing end product cost, this invention is directed more particularly to the manufacture of "cylindrical" columnar lens elements with a principal objective of avoidance of heretofore difficult to handle and messy ion exchange agents, lengthy processing schedules, tedious surface finishing operations, and general costliness.
Another object is to provide for simple, efficient and high quality volume production of the aforesaid lens elements with low investment in capital equipment; and
still another object is to accomplish mass production with an assurance of accurate repetition of article parameters and quality of finish.
Other objects and advantages of the invention will become apparent from the following description.